1. Field of the Invention
The invention relates to an illuminating apparatus for a projection display, more particularly to an illuminating apparatus that utilizes a plurality of primary color light sources to generate input light for a projection display.
2. Description of the Related Art
In a conventional projection display, input light is filtered and separated into color components that are modulated and subsequently recombined to generate an image output.
Referring to FIG. 1, a conventional illuminating apparatus 1 that is used to generate input light for a projection display (not shown) is shown to include an elliptic reflector 11, a single lamp 14 serving as a light source, and a rod integrator 15. The elliptic reflector 11 has first and second focal points 12, 13. The lamp 14 is disposed at the first focal point 12. The elliptic reflector 11 reflects light rays that radiate from the lamp 14. The integrator 15 has an input side 150 coincident with the second focal point 13 such that the light rays reflected by the elliptic reflector 11 converge at the input side 150. Light from the integrator 15 is subsequently processed by 2 condensers 16, 17 and is filtered and separated into primary color components, such as red, blue and green color components.
Referring to FIG. 2, another conventional illuminating apparatus 2 for a projection display 25 is shown to include a single light source 21, a parabolic reflector 22, and first and second lens array integrators 23, 24. The light source 21 is disposed at a focal point of the parabolic reflector 22. The first lens array integrator 23 is disposed between the parabolic reflector 22 and the second lens array integrator 24. The parabolic reflector 22 reflects light rays, which radiate from the light source 21, in parallel toward the first and second lens array integrator 23, 24. Light from the integrators 23, 24 is processed, such as by filtering, color separation and modulation before being projected on a display screen.
The light source used in the aforesaid conventional illuminating apparatuses 1, 2 can be a halogen lamp or an arc lamp, such as a high-voltage mercury lamp, a metal halide lamp and a xenon lamp. The following are some of the drawbacks of the conventional illuminating apparatuses 1, 2:
1. Since the light source is similar to incandescent light, the light therefrom can hardly be separated into pure color components due to limitations of the color separation device, thereby resulting in low color purity of the image output.
2. Due to low color purity, color characteristics are difficult to adjust, thereby resulting in an image output with a narrow color band region and in difficulty in attaining natural color rendering.
3. Due to the high power consumption and high heat generation of the light source, the light source has a relatively short service life. Furthermore, when the single light source breaks down, the conventional illuminating apparatus cannot work.
4. Since ultraviolet and infrared rays in the light source should be filtered prior to color separation, special filter lenses are necessary, thereby resulting in a relatively high cost.
Therefore, the main object of the present invention is to provide an illuminating apparatus that utilizes a plurality of primary color light sources to generate input light for a projection display which can overcome the drawbacks associated with the aforesaid prior art.
According to the present invention, an illuminating apparatus comprises:
a plurality of light sources that generate a plurality of primary color light components;
a reflector unit for receiving the primary color light components from the light sources; and
an integrator having an input side to receive the primary color light components reflected by the reflector unit.